Reusable mercury circuit breaker device



R. E- BLODGETT REUSABLE MERCURY CIRCUIT BREAKER DEVICE April 28, 1964 Filed June 1, 1961 INVENTOR.

r T E m w B 5 D m H m R A TTOR/VE V United States Patent 3,131,273 REUSABLE MERCURY CIRCUIT BREAKER DEVICE RichardE. Blodgett, Holmesbrook Road,

Basking Ridge, NJ. Filed June 1, 1961, Ser. No. 114,177 2 Claims. (Cl. 200-113) This invention relates to circuit breaker devices in general, and more particularly to circuit breaker devices of mercury type.

The present invention contemplates a reusable mercury circuit breaker device in which the heat generated by an overload in a circuit to which the device may be connected, causes the expansion of the mercury and thereby the flow of the latter from a compartment formed in a glass tube into an adjacent compartment through an apertured partition with the consequent evaporation and the forming of an arc, and, finally, the separation of the mercury at a constricted point between the electrodes having their ends in contact with the mercury, the reestablishment of the continuity of the current flow through the mercury at the constricted point being effected by returning the mercury to its respective compartment following the clearing of the overload in the line circuit.

Other novel features and advantages of the invention will appear from the following description and by the claims appended thereto, reference being had to the accompanying drawing in which similar reference characters denote similar parts throughout the views showing modifications of the device.

FIG. 1 is a view of the mercury circuit breaker device of the invention shown partly in longitudinal section, the elements used for reconditioning the circuit breaker to operating condition being shown in normal position;

FIG. 2 is an enlarged view, partly in section, of the circuit breaker shown in FIG. 1, modified for manually effecting the reconditioning of the circuit breaker device to its conducting condition;

FIG. 3 is a view partly in longitudinal section of another modification of the mercury circuit breaker device of the invention;

FIG. 4 is a longitudinal view in section of another modification of the mercury circuit breaker device adapted for use in replacement or ordinary house fuses; and

FIG. 5 is a front view of FIG. 4.

The mercury circuit breaker device of the invention as shown in FIG. 1, consists of a glass container in the form of a tube T, closed at one'end, while a partition 12 divides the glass tube into two compartments Y and W, the compartment Y being filled with mercury into which electrodes 19 and 20 extend.

.The partition 12 also serves as a stop for a plunger member 13 fitted for sliding movement into the compartment W against the tension of a compression-spring 14 having one end abutting against the plunger and its opposite end against a knob 15, screw threaded onto a sleeve 16 soldered onto this end of the glass tube, the spring 14 having such tension as to allow a relatively small amount of mercury normally filling the compartment Y to flow from an opening in the partition into the plunger compartment W upon the occurrence of an overload in the circuit to which the device of this invention may be connected and the consequent expansion and evaporation of the mercury at a constricted point 21 in that compartment to interrupt the current flow caused by the heat generated by such overload, the spring 14 returning the plunger 13 to normal and thereby the mercury back into the compartment Y for reestablishing the mercury continuity and therefore that of the current in the line circuit when the overload condition of the latter has been cleared.

3,131,273 Patented Apr. 28, 1964 The electrodes which are sealed to the glass tube, one on each side of the constriction 21, are in the form of short pieces of wire 19 and 20, each having, as above mentioned, one end immersed into the mercury in position as shown in FIG. 1, filling the compartment Y, the constriction 21 in that compartment forming a region in which the mercury is brought to vaporizing temperature and the formation of an are upon the occurrence of the current overload and thereby causing the breaking or discontinuity of the current at that point, this condition remaining until the normal operation of the line circuit has been effected, at which time the tension of the spring 14 returns the plunger 13 to normal and thereby the mercury into the constricted compartment Y of the glass tube, thus reestablishing the continuity of the current at that point.

In the construction of the circuit breaker device shown in FIG. 2, which is a modification of the device shown in FIG. 1, enlarged, the glass partition 12 which is formed into the glass tube, divides the latter into the compartments Y and W, the compaltment Y being formed with the constriction 21, while the compartment W is in the form of a cylinder fitted with a glass plunger 22, the latter having an extension 22x reduced diameter protruding through a cap 23y of insulating material screw threaded onto the end of a tubular housing, also constructed of insulating material, the plunger 22, in normal position as shown in FIG. 2, giving an indication of the operating condition of the device.

The housing sleeve 18, which, as above mentioned, is constructed of insulating material, serves for supporting the glass tube at both ends, and one of its ends is formed with an enlarged portion on which is fitted a metallic screw threaded shell 24x provided for engaging a similarly screw threaded socket, not shown, in the manner of an ordinary lamp bulb or fuse. The shell 24x connects with the mercury in compartment Y to one side of the constriction 21 through a wire conductor 12x fused to the glass, while a conductor 25, in the form of a plug, has its reduced end extending into the wall of the glass tube in axial and concentric relation to the enlarged portion of,-

the insulating sleeve 18 in contact with mercury to the other side of the constriction 21, but it is to be noted that the concave minuscus of the mercury at the partition point effectively retain the mercury when under normal temperature condition from flowing into the plunger compartment.

In the operation of the circuit breaker device shown in FIG. 2, an overload of the current in the energizing circuit to which the device may be connected, like in the device shown in FIG. 1, causes the heating and thereby the expansion and the flow of the mercury from the compartment Y through the opening it) in the partition 12 into the cylindrical compartment W while pushing the plunger 22 from normal position to the operated position indicated by its extension 22x as shown in dotted lines, under this condition the continued heating of the mercury and the consequent increased resistance at the constricted point 21 causes the vaporizing and arcing of the mercury, and finally the interruption of the current flow, the position of the plunger giving a. visual indication of the discontinuity of the current.

In this circuit breaker device, the manual operation of plunger 22 to its normal position shown in FIG. 2,

is effective to force the mercury back into the constricted In the construction of the circuit breaker device shown in FIG. 3, like in the construction of the circuit breaker device shown in FIG. 2, the glass partition 12 divides the glass tube into the two compartments Y and W. The conductor 12x has one end in contact with the mercury in the compartment Y and its other end connects with the stud 25 embedded into the enlarged end of the insulating housing forming the plug, while a conductor 28 connects to the screw threaded shell 24x fitted over this end of the plug, and its other end to an electrode in the form of a stud 29 sealed to the glass tube in contact with the mercury at this end of the tube, the latter and the conductors 12x and 28 being fitted into the cylindrical portion of the housing 18 while a cap 18x serves as a guard at this end of the glass tube.

In the operation of this circuit breaker device, like in the operation of the circuit breakers shown in FIGS. 1 and 2, an overload in the circuit causes the expansion of the mercury in the compartment Y and the subsequent vaporizing of the latter at the constricted point 21 following the forcing of an amount of mercury into the compartment W of the device, and thereby interrupting or breaking the circuit at the constricted point which is re:- established upon the cooling of the glass tube. It has been found that in this modification a partial vacuum in the glass tube lowers the temperature at which the device operates.

In this device, the circuit, through the mercury, is conveniently restored to operating condition by removing the device from its socket, placing it in a position for permitting and facilitating the self return of the mercury to the constricted compartment Y of the glass tube, this operation may be activated by imparting a slight jerk to the device and placing it back into the socket, but in case the overload in the line circuit is still present, an identical operation of the device to that above described will result.

In the construction of the circuit breaker device shown in FIGS, 4 and 5, the glass tube is shaped to represent a substantially U-shaped figure having its ends 30 and 31 closed, while the curved portion of the glass tube is formed with a constriction 32, and into the parallel sides 33 and 34 of the tube are formed the partitions 35 and 36 which divide the glass tube into three compartments Y and WW1, each partition having a relatively small centrally located opening as 37 and 38 serving as passageways for permitting the mercury in the compartment Y to flow from this compartment into the compartments W and W1 formed, as above mentioned, by the parallel sides of the glass tube.

An electrode 39 from the mercury connects directly with a disc-shaped conductor member 40, While an electrode 41 connects from the mercury with the metallic shell 24x, the latter being fitted over a plug of molded insulating material enclosing the parallelly disposed sides of the glass tube and insulating the conductors 39 and 41, while the shell 24x is provided at its front end with a knurled rim 50 adapted to be gripped by the fingers for facilitating the placing and removing the circuit breaker from its socket in the manner of the well-known house fuse.

In the operation of the circuit breaker device of the invention, like in the operation of the devices shown in FIGS. 1,v 2 and 3, an overload in the circuit causes the expansion of the mercury and the consequent evaporation of the latter at the constricted point 32 of the glass tube, such evaporation causing the flow of a small quantity of the mercury from the compartment Y into the compartments W and W1 forming the parallel sides of the U- shaped glass tube to break the current connection.

In this modification, like that of the device shown in FIG. 3, the circuit may be reestablished by removing the device from its socket and placing it in a position as to permit the return of the mercury to the constricted cornpartment Y of the tube, which is facilitated, as above mentioned in connection with the device shown in FIG. 3, by imparting a light jerk to the device following the cooling and condensation of the mercury vapor in the glass tube.

It is understood that minor changes may be made to the circuit breaker device of the invention as to shape, size and material, without departing from the scope of the appended claims.

What I claim is:

l. A reusable mercury circuit breaker device consisting of a substantially U-shaped tubular glass container formed with a constriction at its curved portion, a partition disposed on each side of said constricted curved portion dividing said tube into three contiguous compartments, mercury material filling said constricted curved compartment, electrodes in the last mentioned compartment having one of their ends in contact with the mercury, each of said partitions having a centrally disposed opening for permitting the flow of mercury from said curved constricted compartment into each of the other of said compartments upon the heat and the consequent. expansion of the mercury generated at the constricted point of the curved portion of said glass tube by an overload in the energizing circuit to which the device may be connected for interrupting such current in said circuit, a cylindrically-shaped plug member of insulating material forming a housing for said U-shaped glass container, the opposite ends of said electrodes forming terminals embedded into said housing and protruding therefrom for connection with an energizing circuit.

2. A reusable mercury circuit breaker device comprising a glass tubing closed at both ends, a glass partition into said tubing dividing the latter into two compartments, the wall of one of said compartments shaped to form a constriction, electrodes extending through the wall of said glass tubing in said constricted compartment one on each side of said constriction, mercury material filling said constricted compartment contacting with said electrodes, said glass partition having an opening through which the mercury is forced from said constricted compartment into the other of said compartments upon the heating and expansion of the mercury caused by a current overload and the consequent vaporizing of the mercury in the constricted compartment to effect the breaking of the circuit in said constricted compartment, a housing of insulating material extending over the length of said glass tubing, a cap member fitted over one end of said housing, said cap member cooperating with said housing for enclosing said glass tubing, a conducting wire embedded in said housing connecting with one of said electrodes, a stud member fitted at one end of said housing and connecting with said conducting wire, a conducting sleeve encircling one end of i said housing, and another conducting wire disposed in said housing connecting with the other of said electrodes and said conducting sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 

2. A REUSABLE MERCURY CIRCUIT BREAKER DEVICE COMPRISING A GLASS TUBING CLOSED AT BOTH ENDS, A GLASS PARTITION INTO SAID TUBING DIVIDING THE LATTER INTO TWO COMPARTMENT, WITHIN A SPACE, SAID DETECTOR COMPRISING SEALED ELONGATE HIGHLY HEAT CONDUCTIVE TUBE MEANS FRO CONTAINING AIR AND ADAPTED TO BE MOUNTED IN THE SPACE WHERE THE INCREASE IN TEMPERATURE IS TO BE DETECTED, SAID TUBE MEANS HAVING AN INNER DIAMEEROF ABOUT 0.75 INCH AND HAVING A VOLUME OF ABOUT 7.5 CUBIC INCHES AND BEING CAPABLE FO PRODUCING AN INCREASE IN PRESSURE OF THE AIR THEREIN AT A RATE OF ABOUT 0.5 INCH OF WATER IN ABOUT 3 SECONDS UPON A SUBSTANTIALLY INSTANTANEOUS INCREASE IN TEMPERATURE OF ABOUT 0.5*F. OF THE AIR AMBIENT TO SAID TUBE MEANS, SAID TUBE MEANS HAVING A WALL THICKNESS OF ABOUT 0.003 INCH AND BEING SUFFICIENTLY RIGID TO PROVIDE IT WITH A FIXED VOLUME AND THE OUTER SURFACE OF SAID TUBE MEANS BEING DARKENED TO IN- 